Sayyiduna Sa'd bin Ubadah (may Allah be pleased with him) said that he came to the Prophet (peace and blessings be upon him) and asked: "Which charity is best (which do you like most)?" He (peace and blessings be upon him) said: "Giving water to drink."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7804
It is narrated from Sayyiduna Abu Sa'id (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Any Muslim who clothes someone in his need, Allah Almighty will clothe him with the silk of Paradise; whoever feeds a Muslim in his hunger, Allah Almighty will feed him from the fruits of Paradise; and whoever gives a Muslim water to drink in his thirst, Allah will give him to drink of the sealed pure drink [Al-Mutaffifin: 25] (the finest drink)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7805
It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "Once a man was walking along a road when he felt severe thirst. He found a well, went down into it and drank. Then he came out and saw a dog panting and licking the moist earth because of thirst. The man said: 'This dog has suffered the same thirst that I suffered' (in the narration of Qutaybah: 'like what I suffered').
Then he went down into the well, filled his leather sock with water, held it in his mouth until he climbed up, and gave the dog water to drink. Allah Almighty appreciated his deed and forgave him." The Companions (may Allah be pleased with them) said: "Is there a reward for us even in animals?" He (peace and blessings be upon him) said: "There is a reward in (serving) every living creature with a moist liver."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7806
Sayyiduna Suraqah bin Malik bin Ju'shum (may Allah be pleased with him) said that he came to the beloved Prophet (peace and blessings be upon him) during his illness and said: "Tell me, if a stray animal comes to the trough of my camels, will I get a reward for giving it water?" He (peace and blessings be upon him) said: "Yes! There is a reward in (every) being with a living heart."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7807
Suraqah bin Malik bin Ju'shum (may Allah be pleased with him) said: I asked the Messenger of Allah (peace and blessings be upon him) about a stray camel that comes to my trough: if I give it water, will I get a reward? He (peace and blessings be upon him) said: "Yes, there is a reward in every being with a living heart."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7808
Kudayr al-Dabbi (may Allah have mercy on him) said that a Bedouin came to him (peace and blessings be upon him) and said: "Tell me of a deed that will bring me close to it (Paradise) and keep me far from the Fire." He (peace and blessings be upon him) asked: "Will you act upon them?" He said: "Yes." He (peace and blessings be upon him) said: "Speak justly and give away the surplus of your wealth." He said: "By Allah, I am not able to speak justly at every moment, nor am I able to give away the surplus of my wealth." He (peace and blessings be upon him) said: "Then feed people and spread the greeting of peace." He said: "This too is difficult." He (peace and blessings be upon him) said: "Do you have camels?" He said: "Yes." He (peace and blessings be upon him) said: "Then pick one camel from your camels and a waterskin, then go to households who drink water only every other day, and give them water to drink. Perhaps your camel will not perish and your waterskin will not tear before Paradise becomes binding for you." He said: The Bedouin went off saying Allahu akbar. The narrator said: Neither did his waterskin tear nor did his camel perish, until he was killed as a martyr.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الزكاة / 7809